This invention pertains generally to the cooling of a hermetic compressor pump used in cryogenic refrigeration. During operation, the pump compresses a mixture of oil and helium. The purpose of the oil is to absorb the heat produced in compressing helium and to provide lubrication to the pump. From the compressor, the mixture exits a feed line in which the oil is separated from the mixture. Conventional methods use an oil separator and then an oil adsorber to filter the oil out of the mixture. Once separated, the gas is then pumped to the cold head of a cryogenic refrigerator such as a Gifford-MacMahon cryogenic refrigerator disclosed in U.S. Pat. No. 3,218,815 to Chellis et al. After traveling through the refrigerator, the gas is returned to the compressor through a return line to start the process over again.
As a result of compressing helium, rather than freon which is used in other refrigeration systems, more heat is produced by the compressor pump. In order to maintain operating efficiency and prolong the life of the pump, this heat by-product must be removed.